Data storage systems store data at the request of user. For example, storage controllers control access to data storage media and memories in response to read and write requests. The storage controllers may direct the data in accordance with data storage devices such as RAID (redundant array of independent disks), JBOD (just a bunch of disks), and storage with other redundancy and security levels.
As an example, an IBM® ESS (Enterprise Storage Server) such as a DS8000 has redundant clusters of computer entities, cache, non-volatile storage, etc., called “central electronics complexes” or “CECs”. The CECs may be partitioned into actual or virtual “storage pools” or field images running within the system, where each partition is also redundant, including partitions within each of the CECs.
Data storage systems additionally offer the user the capability to delete the data. As an example, where the data is stored in the form of volumes, the deletion of one or more volumes may be done with Command Line Interface (CLI) commands or with Graphical User Interface (GUI) commands.
To prevent the inadvertent deletion of a volume, storage controllers use an overall control switch and parameters or modifiers, as discussed in the copending application Ser. No. 12/908,284, to control the behavior of the volume delete. For example, when the overall control switch is set to “ON” value, the user must specify an override parameter in the CLI command to delete a volume. Without the override parameter, the storage controller rejects the volume delete request if the volume meets certain criteria such as: the volume is on-line to a host, or the volume is in a Copy Service (CS) relationship. If the overall control switch is set to “FALSE” value, the volume can be deleted without additional CLI parameters or modifiers. In another case, even though the overall control switch is set to “ON”, it is possible for the user to remove a volume from its (CS) relationship or to remove it from its volume group such that it is no longer on-line to a host. This is possible when the data is constantly being revised, and an old version of a volume is thereby replaced by a new version, and the previous version is allowed to be deleted.
The deleted version(s) may comprise important information that was (perhaps accidentally) not carried forward to the current version, conceivably leading to failure for applications running to the volume as well as the data loss or loss of integrity associated with the removal of the volume.